A356.2 aluminum alloy has excellent characteristics such as good flowability, no tendency of hot cracking, low linear shrinkage, small specific gravity, good corrosion resistance, and is the material mainly used in automobile hubs. However, as-cast structure of the A356.2 aluminum alloy without being subjected to refinement and modification treatment is a coarse sheet-like or needle-like eutectoid silicon and alpha-Al dendritic structure with relatively low mechanical properties. Therefore, it is necessary to add modification elements and grain refining elements so that morphology of the eutectoid silicon is transformed from the coarse sheet shape or needle shape into a fine spherical shape or rod shape, and simultaneously alpha-Al grains are refined, so as to improve usability of the A356.2 aluminum alloy and expand the range of its applications. At present, refiners for the A356.2 aluminum alloy frequently used in industrial production include Al—Ti—B, Al—Ti—C, Al—Ti—B—C and the like.
In the prior art, CN102886511A discloses a method of preparing an Al—Ti—C grain refiner. The refiner is prepared by adding TiC to molten aluminum. The involved TiC is nanoparticles with high cost as a material and complex preparation process. Additionally, it is necessary to use argon or nitrogen to disperse the nanopowder to a melt, which increases the complexity of the process, prolongs the whole process cycle, is difficult to control and does not facilitate industrial production.
In the prior art, CN103667759A discloses an Al—Mg—Si series alloy alpha-Al grain refiner and a preparation method thereof. According to the method, three kinds of power, i.e., Ti powder, Bi powder and Cr powder, need to be mixed, and then the obtained mixture is ground into 200-400 mesh powder, which prolongs the process duration. Additionally, the powder may be used only after the powder is tightly packaged by aluminum foil and baked for 30 minutes at the temperature of 200-250 degrees Celsius, which increases the complexity of the process and does not facilitate industrial production.
In the prior art, CN103589916A discloses a rapid solidification Al—Ti—B—Sc master alloy refiner and a preparation method thereof. The refiner is a crystalline material with a microstructure consisting of alpha-Al as well as micrometer-sized TiAl3, TiB2, AlB2 and Al3Sc crystal phases. Micrometer-sized precipitated phases provide limited nucleation particles, thus limiting the refinement effect of elements.
In conclusion, the aluminum alloy refiner in the prior art is less likely to be widely applied due to relatively high cost, or the application of the aluminum alloy refiner in production is limited due to complicated using steps and process.